Gateway toward efficient and miniaturized A 2 B 2O7-type fluorite structure-based energy storage devices.

Defect fluorite structure with A 2 B 2O7 composition exhibits an intense potential for utilization in modern smart electrical devices. Efficient energy storage with low loss factors like leakage current makes them a prominent candidate for energy storage applications. Here we report a series of the form Nd2-2x La2x Ce2O7 with x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0, synthesized via a sol-gel auto-combustion route. The fluorite structure of Nd2Ce2O7 is slightly expanded with the incorporation of La without any phase transformation. A gradual replacement of Nd with La causes a decrease in grain size, which increases the surface energy and thus leads to grain agglomeration. The formation of exact composition without any impurity element is confirmed by energy-dispersive X-ray spectra. The polarization versus electric field loops, energy storage efficiency, leakage current, switching charge density, and normalized capacitance, which are considered key features of any ferroelectric material, are comprehensively examined. The highest energy storage efficiency, low leakage current, small switching charge density, and large value of normalized capacitance are observed for pure Nd2Ce2O7. This reveals the enormous potential of the fluorite family for efficient energy storage devices. The temperature-dependent magnetic analysis exhibited very low transition temperatures throughout the series.

Isolation of alpha-spinasterol from Amaranthus spinosus stems / Aislación de alfa-spinasterol de ramas de Amaranthus spinosus

alpha spinasterol was identified in stems of Amaranthus spinosus. The structure was obtained by spectroscopic methods and comparison with literature data.

alfa spinasterol fue identificado en ramas de Amaranthus spinosus. La estructura fue obtenida por metodos espectroscópicos y por comparación con datos de literature.

Phytochemical and antimicrobial investigation of Luffa cylindrica / Investigacion fitoquimica y antimicrobiana de Luffa cylindrica

3-hydroxy-1-methylene-2,3,4,4-tetrahydroxynapthalene-2-carbaldehyde (1), 22,23-dihydroxy spinasterol (2) were isolated from petroleum ether extrct of the fruits of Luffa cylindrical. The structures of the isolated compounds were elucidated by extensive spectroscopic studies including IR and high field NMR analysis.Petroleum ether extract (i.e. crude extract) exhibited mild to moderate antimicrobial activity. This is the first report of isolation of compound of 1 – 2 from this species.

3-hydroxi-1-metilen-2,3,4,4-tetrahidroxinaftalen-2-carbaldehido (1), 22,23-dihidroxispinasterol (2) fueron aislados de un extracto en eter de petróleo de la fruta de Luffa cylindrica. Las estructuras de estos compuestos fueron deducidas por estudios espectroscópicos incluyendo IR y RMN de alto campo. El extracto crudo en éter de petróleo mostró actividad antimicrobiana de leve a moderada. El presente estudio representa el primer reporte de estos compuestos en L cylindrica.

Investigation of the physical properties of spray-dried stabilised lysozyme particles.

The aim of this study was to investigate the effect of the composition of formulations on the physical properties, including glass-transition temperatures (Tg) and aerodynamic-related characteristics, of spray-dried lysozyme particles. The Tg, as determined by differential scanning calorimetry, of spray-dried lysozyme formulations was found to be dependent upon the type and amount of excipient(s) included in the formulation. In addition, the Tg of sucrose-containing particles appeared to be raised markedly by the inclusion of trehalose, but not by dextran. The surfaces of all spray-dried particles were shown by scanning electron microscopy to be smooth with some containing characteristic dimples, typical of spray-dried material, and the morphology appeared to be independent of variation in excipient composition. However, the volume median diameters (VMD) of spray-dried powders, as determined by laser diffraction, were found to depend upon the amounts of excipients. The fine particle fraction of enzyme delivered to the lower stage of a twin-stage impinger from lysozyme-trehalose 1:1 powders appeared to be greater than that from lysozyme-sucrose 1:1 particles (22.5% vs 15.9%) when dispersed via a Rotahaler although a similar dispersibility of the two formulations (39.6% vs 36.7%) was found from a glass inhaler. In general, spray-drying was demonstrated to be feasible to produce respirable particles of the stabilised model protein, with Tg of the formulations being > 30 degrees C higher than room temperature.

Effects of sucrose and trehalose on the preservation of the native structure of spray-dried lysozyme.

PURPOSE: To investigate the effects of sucrose, trehalose, sucrose/ dextran mixtures, and sucrose/trehalose mixtures on the preservation of the native structure of spray-dried lysozyme in the solid state. METHODS: The intensity of the alpha-helical band and the melting enthalpies (deltaH(m)) of spray-dried lysozyme in the dried form and in aqueous solution were obtained using second derivative FTIR and differential scanning calorimetry (DSC) respectively. RESULTS: The intensity of the alpha-helical band and the deltaH(m) of spray-dried lysozyme obtained were linearly correlated and both suggest that the stabilization of lysozyme in the dried form was excipient concentration-dependent with a close to maximum stabilization being conferred by sucrose or trehalose at a mass ratio 1-2 (sugar:enzyme). Sucrose appeared to be more effective than trehalose on a weight by weight basis whilst stabilizing effects of dextran/sucrose or trehalose/ sucrose mixtures were found to be additive. CONCLUSION: Dehydration during spray drying was considered the main stress to the denaturation of lysozyme. A major effect of the sugars in protecting lysozyme against dehydration was attributable to hydrogen bonding between the sugar and protein molecules, which lead to an increase in the change in the negative value of the free energy between native and denatured states.

Protective mechanism of stabilizing excipients against dehydration in the freeze-drying of proteins.

PURPOSE: To investigate the influence of type and amount of excipient on the preservation of the native structure and the biologic activity of freeze-dried lysozyme and catalase. METHODS: The secondary structure of protein in the dried form and in aqueous solution was obtained using second derivative infrared spectroscopy and circular dichroism spectra respectively whilst the activity was determined using bioassay. RESULTS: Small molecular excipients (glycerol, sorbitol, 1,6-anhydroglucose, sucrose, and trehalose) were found to stabilize the activity and/or the native structure of freeze-dried lysozyme and catalase, despite the processing temperatures being above Tg' of excipent-protein mixtures. The preservation of catalase activity required excipient to be present at a lower excipient to enzyme mass ratio than that necessary to preserve native structure in the dried form. Combining dextran with sucrose synergistically protected the native structure of catalase but preserved the activity in an additive manner. CONCLUSION: The results indicate that the stabilization of catalase and lysozyme by excipients during dehydration was mainly due to water substitution rather than the formation of glass; the latter appearing not to be a prerequisite during freeze-drying.